Sloping grades can present a variety of landscaping problems. Erosion is an example of one such problem. Rain can wash away topsoil and expose the roots of plants, which in turn may cause the plants to die. A low level of water infiltration is also a problem that may be an issue when landscaping on a slope. Since water from rainfall or a sprinkler system tends to run down the grade, the water doesn't have a chance to soak into the ground and nourish plants or shrubs used in the landscaping. Plants and greenery at the bottom of the slope tend to receive too much water, whereas plants at the top of the slope may not get enough. Further, fertilizer tends to wash down the slope, which may leave plants at the top undernourished and plants at the bottom receiving too many nutrients. These and other conditions make it difficult to grow plants on a sloping grade.
A variety of solutions have been previously proposed for minimizing problems associated with maintaining landscaping on sloping grades. Various solutions include ground covers, terracing, re-grading, and retaining walls. For steeper hills, or those in areas that can't be re-graded easily, terracing may solve slope related problems by creating smaller, level planting beds. To assist in retaining water in the vicinity of the plant's root system, it has been proposed that water impermeable root barrier envelopes may be installed around the roots. A problem with employing root barrier envelopes is that while the upper surface near the plant may retain water, the lower regions may receive insufficient water, aeration and nutrients, which can adversely affect the growth characteristics of the plant. A common erosion prevention option employed by landscapers is to use mulch as a ground cover. Mulches, such as straw, bark, sawdust, leaves, wood pulp and fibers, clippings, and compost tend to absorb moisture and release it slowly, but can be washed away by heavy rains, thus exposing the soil to erosion. Woven fabric matting or plastic sheets may also be used on especially steep slopes. Adding large rocks in steeper areas, or perhaps small rock gardens at various points along a slope, may slow the flow of water down the slope. While these methods may be reasonably effective at minimizing soil erosion on a sloping grade, they may not be very effective at minimizing water runoff, which may ultimately deprive the plants of essential moisture and nutrients.